The prior art features pneumatic carrier transport systems with carrier reception chambers for receiving a carrier. An example is found in bi-directional carrier transport systems in which a bank teller carrier (a transport tube cylinder) is transported back and forth between a customer station and a teller station. Examples of bi-directional carrier transport systems are found in U.S. Pat. Nos. 5,147,154; 5,211,513; 5,562,367; 7,153,065, each to the current inventor Lowell Scott and sharing a common assignee with the present assignee, Hamilton Safe Company of Fairfield, Ohio, USA. In such systems, the carrier reception chambers need to be sufficiently sealed off to achieve the desired pressure level state at the desired time (e.g., a pressurized state is formed in the reception chamber as the carrier is braked to achieve a soft landing in that reception chamber). A low pressure vacuum state is formed ahead of the carrier and/or a higher pressurized state is formed behind the carrier to place the carrier in motion within the carrier transport system as through use of a turbine box. Once the carrier is properly located within the reception chamber and the system is placed in user access mode (e.g., through release of a pressure within the reception chamber as in a return to an atmospheric pressure state or into a “static” state by a dissipation of air behind a carrier following braking) a user (e.g., bank teller) accesses the transport carrier by opening an access cover. This typically entails rotating a cylindrical section of a support housing for receiving the carrier. Thus, the rotating cylindrical section represents an access door, as in an access door support cylinder with corresponding access opening to be covered by the access door.
To achieve the desired pneumatic seal levels, particularly at the time the transport system is pressurized, the access doors of the prior art are connected with an access door support in a tight seal arrangement as in one where the access cover is in an interference seal fit relative to a sealing device provided on the access door support when at the closed and open states and in an interference fit relative to the bearing support provided by an access door support structure on which the access door rides in going between fully open and fully closed states. This interference contact leads to difficulty in user access as the access cover can be difficult to open under such a seal retention arrangement. In addition, even if the cover moves relatively smoothly in going from a closed to open state or vice versa, there is a associated with that movement a squeaking or moaning noise due to the interrelationship of the bearing and/or sealing structure relative to the access cover during movement of the access cover. Many prior art seals are also often made of a material that is designed with a high degree of elasticity to provide a good sealing function, but which material is prone to relatively rapid wear due to the tight fit relationship. Thus, after a period of use, the seal assembly can degrade and so too then does the carrier transport efficiency due to pressure leakage, for example. Moreover, various types of interference seals have been utilized that are formed of various materials such as steel, aluminum, and plastic. These types of seals present their own problems such as having to either be initially squeaky tight then loose over time and/or hard to manufacture to provide a good seal quality. There are also tangential seals which also are difficult to seal tight and thus generally necessitate the addition of some sort of detent to hold the door closed against the seal.